This invention relates to a cabling handling apparatus and to a method of using the same.
The invention primarily but not exclusively relates to such an apparatus and method for handling fibre optic cables which comprise a fibre including a core and cladding with a different refractive index, the fibre being covered with one or more outer layers which give the fibre optical and mechanical protection.
Fibre optic cables are used to transmit data as pulses of light along the core, which fibre may have a diameter of only 50-300 microns. Also, such fibres are typically made of glass fibre. Thus such cables require particularly careful handling.
To allow such cables to be joined to another cable or to a receptor of an optical data handling apparatus, a fibre optic cable is terminated in a termination through which the fibre extends to an optical end surface. The outer protective layer or layers may be mechanically retained by the termination.
It is desirable to be able to attach a termination to the end of the fibre optic cable in situ, for example on-board an aircraft, perhaps in confined conditions.
Conventionally, to perform work operations on a fibre optic cable in such circumstances requires considerable manual dexterity and because there may be little spare length of fibre optic cable, reworking of cable terminations may not be possible.
According to a first aspect of the invention we provide a handling apparatus for handling cables including first and second members connected together for relative movement between an open position in which a cable may be inserted between the members, and a closed position in which the cable is securely held between the members with a part of the cable projecting outwardly of the members, whereby the first and second members may be held whilst work operations are carried out on the projecting part, the apparatus further including an elongate indicating means received by the first member for axial sliding movement relative to the first member, the indicating means having an indicator and a plurality of markings arranged at predetermined positions axially of the indicating means, the indicating means being slidable so as to bring the markings severally into registry with a reference part of the first member whereby the indicator is positionable relative to the first member at predetermined positions relative to the projecting part of the cable when the first and second members are closed together, so that the indicator may indicate appropriate portions of the projecting part on which particular work operations are to be carried out.
Thus utilizing the apparatus of the present invention, the cable may be securely held by the apparatus which in turn may be more easily handled by an operative. Because of the provision of the indicating means, an operative may readily ensure that only a desired length of the outer layer for example of a fibre optic cable is removed from the core in a work operation for a particular cable termination type. Thus the indicating means may be specific to a cable type and termination type, but may be interchangeable with an alternative indicating means for alternative cable and termination types.
Preferably retaining means are provided to retain the first and second members in their closed position. Such a retaining means may comprise a clamping member which is connected to one of the first and second members, so as to be moveable into a retaining condition in which the clamping member engages with the other of the first and second members to retain the first and second members in their closed position.
For example the clamping member may be connected to the one member by link means, the link means being pivotally connected at or towards one end to the first or second member and at or towards an opposite end to the clamping member. Thus the other of the first and second members with which the clamping member engages, may have a recess in which the clamping member may be received when in the retaining condition.
However alternative means to maintain the first and second members closed may be provided although the arrangement described is particularly useful where at least one of the first and second members provides an elongate recess along which the cable extends when held between the members. The first and/or second member may include resilient material which is resiliently deformed when the first and second members are closed together with the cable therebetween, the resilient material being provided by an insert which includes the recess for the cable.
The indicating means may include an elongate body received in an axially extending opening of the first member, the opening extending generally parallel to the cable, and the markings being provided along the body. The indicator may be provided on a transversely extending part of the indicating element, which transversely extending part extends towards the projecting part of the cable. Thus the indicator may readily indicate e.g. a position along the projecting part where the portion on which a work operations is to be carried out, commences.
The body of the indicating means may have provided therealong, a recess corresponding to each marking, and the first member may have resiliently biased detent means severally engageable with each such recess, so that when the indicating element is slid so as to bring a marking into registry with the reference part of the body, the indicator is positively held at the predetermined position by the engagement of the detent in a corresponding recess. Of course other means to facilitate sliding of the indicating means and retention of the indicating means in a desired position may alternatively be employed, although the arrangement described is particularly simple in construction.
According to a second aspect of the invention we provide a method of handling a cable to facilitate the performing of a work operation thereon using a cable handling apparatus according to the first aspect of the invention characterised in that the method comprises opening the first and second members, inserting the cable therebetween with a part of the cable projecting outwardly, closing the first and second members securely to hold the cable, sliding the indicating means to bring a marking appropriate to a work operation to be carried out into registry with the reference part of the first member, so that the indicator of the indicating means indicates an appropriate portion of the cable on which to perform the work operation.
The invention is particularly useful for handling a fibre optic cable during the preparation of such a cable for termination in a cable termination.
Thus according to a third aspect of the invention we provide a method of terminating a fibre optic cable which includes a fibre including a core and at least one outer protective layer, in a termination which includes a first part for receiving the cable including the outer layer, and a second part for receiving a projecting fibre part so that the fibre extends to an optical end surface of the second termination part, the first and second termination parts being axially arranged, the method including performing a work operation on the fibre optic cable to remove the outer layer to leave a desired length of projecting fibre, characterised in that to perform the work operation, the cable is inserted between first and second members of a cable handling apparatus according to the first aspect of the invention and the indicating means thereof is slid to a predetermined position relative to the first member and with a marking thereof in registry with the reference part so that the indicator indicates a portion of the projecting part of the cable which corresponds in length to the desired projecting fibre length, and the outer layer is removed from the indicated portion using a tool to leave the projecting fibre projecting from an end of the remainder of the cable.
In order that the very end of the fibre is in perfect condition for light transmission, the fibre has carefully to be cut to ensure that the core is not split or cracked, which such damage could result in data loss or corruption. Such careful cutting is conventionally performed after the fibre has been inserted into a termination, by what is known as a cleaving process. Whereas the method of the invention may be applied where the fibre is cleaved subsequent to insertion into the termination, preferably subsequent to performing the work operation to remove the outer layer, a further work operation is carried out, the further work operation including cleaving the projecting fibre to a length such that when the cable is received in the termination, a desired length of the projecting fibre extends from the optical end surface of the second part of the termination, the method including, subsequent to performing the first work operation, sliding the indicating element to bring a second marking into registry with the reference part, so that indicator indicates an appropriate position of the projecting fibre at which to cleave the fibre.
Thus the fibre may be cleaved to the final desired length prior to insertion into the termination.
Desirably, to ensure that the cleaved end of the fibre is not prone to damage subsequent to being inserted into the termination, e.g. while adhesive in which the fibre is conventionally set cures, the method may include inserting into the second part of the termination ahead of the projecting fibre part, an adhesive, the projecting fibre when inserted into the second part of the termination, causing some of the adhesive to flow from the second part onto the optical end surface of the second part, the position of the second marking of the indicating means being such that the projecting fibre is of such length as a result of cleaving, the projecting fibre which extends from the optical end surface of the termination is within the adhesive on the optical end surface.
Where the cable has a plurality of outer protective layers, a different length of each of which requires removal, the method may include, subsequent to performing a first work operation to remove an outermost layer thereof, performing at least one subsequent work operation to remove a different length of an inner outer layer, the method including subsequent to performing the first work operation, sliding the indicating means to bring another marking into registry with the reference part, so that the indicator indicates an appropriate portion of the cable from which to remove the inner outer layer in a subsequent work operation.
According to a fourth aspect of the invention we provide a method of terminating a fibre optic cable which includes a fibre and at least one outer protective layer, in a termination which includes a first part for receiving the cable including the outer layer, and a second part for receiving a projecting fibre only so that the fibre extends to an optical end surface of the second termination part, the first and second termination parts being axially arranged, characterised in that the method includes subsequent to performing a work operation to remove the outer layer, carrying out a further work operation, the further work operation including cleaving the projecting fibre to a length such that when the cable is received in the termination, a desired length of the projecting fibre extends from the all optical end surface of the second part of the termination.